|Sony models often have TWO model numbers. Their support on the Sony web site is for only ONE of the two numbers.|
You have quoted the wrong one.
I'm assuming it's a US model.
(If it isn't, you will need to go to a Sony web site for the the country or region it was bought it in, and find the same or a similar page as this one, next.)
Click on How do I find my model number
Then search for support for THAT model number.
( If you enter PCG-7Z1L on the Enter your model number box, search with that, you will see a list of MANY possible models.
If you have a pre-configured model, if Windows is not working and/or if it is but the methods in Windows described to find the proper model number yield no result, if you look in your bios Setup it MAY be shown there - at least, it is shown there on old Sony laptops.)
If you still can't find what you're looking for, we need you to quote the OTHER model number, and for you to tell us which country it was bought in,